The appeal follows a US supreme court ruling last month. The decision threatens to unravel some of the biggest white-collar crime cases in recent years, not just that of Black but also of Jeffrey Skilling, the former chief executive of energy firm Enron. The supreme court used an appeal by Black and Skilling to limit the use of a criminal statute known as the honest services law, which targets individuals for not fulfilling the duties of their office. The court ruled in decisions written by supreme court judge Ruth Bader Ginsburg that the statute applied only to instances of bribery or kickbacks. Skilling's lawyers said the ruling was fatal to the government's case. Black's lawyers this week applied for bail. The question now will be the extent to which prosecutors relied on the honest services provision in convincing juries that considered the two cases. The same appeals court rejected Black's appeal two years ago, before the supreme court decision. If the convictions are overturned, prosecutors are unlikely to resurrect efforts to retry him, according to legal experts.

What was Black convicted of?

Along with three other former Hollinger International executives, Black was convicted in 2007 of swindling the media empire's shareholders out of $6.1m (£3.9m). He was acquitted of nine other charges, including racketeering and wire fraud. Black was also convicted of obstruction of justice after jurors saw a video of him carrying boxes of documents sought by government investigators out of his offices, loading them into his car and driving off with them.

Does Black face other legal problems?

Black and former Hollinger International executives face a raft of civil lawsuits. The US internal revenue service is also after Black, who surrendered his Canadian citizenship to be ennobled Lord Black of Crossharbour in 2001. The IRS claims Black owes almost $71m in unpaid taxes and penalties. The IRS alleges that Black failed to report and pay taxes on income stemming from personal use of Hollinger's corporate jets, the use of corporate money to acquire papers written by president Franklin Roosevelt and Roosevelt's private secretary, and Hollinger's purchase in 2000 of a $5.9m New York apartment for his use. Black says he was not required to file tax returns because he was not a US resident.

What are Black's assets?

Black's net worth was estimated to be $400m at his peak. His fortune is considerably less now but it is difficult to pin down as investigators do not know whether he salted money away in alleged offshore accounts. Black denies any accusations to do with such accounts. What we do know is that the loyal Lady Black, the former columnist Barbara Amiel, has a 26-carat diamond worth $2.6m. There is a house in Palm Beach, Florida, worth $34m, where his wife lives, and another in Toronto, said to be leveraged "to the hilt". Black sold his Kensington home for $25m and an apartment on Park Lane in New York for $8.5m.

What happened to Hollinger International?

The Barclay brothers acquired Hollinger International's UK titles, including the Telegraph, for £665m in 2004. The Jerusalem Post was sold in the same year to Mirkaei Tikshoret and CanWest, Canada's biggest media group, for $13.2m. In 2006, Hollinger International changed to the Sun-Times Media Group. It filed for bankruptcy last year and was bought in October by the Chicago financier James Tyree and a team of investors for $5m.